Problem: Simplify the following expression: $n = \dfrac{1}{10y} + \dfrac{7}{3y}$
Solution: In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $10y$ and $3y$ $\lcm(10y, 3y) = 30y$ $ n = \dfrac{3}{3} \cdot \dfrac{1}{10y} + \dfrac{10}{10} \cdot \dfrac{7}{3y} $ $n = \dfrac{3}{30y} + \dfrac{70}{30y}$ $n = \dfrac{3 +70}{30y}$ $n = \dfrac{73}{30y}$